Control system for sub-sea apparatus



1967 M. HUBBY CONTROL SYSTEM FOR SUB-SEA APPARATUS 2 Sheets-Sheet 1Filed Aug. 24, 1964 wm QSQ QW Aug. 29, 1967 L. M. HUBBY 3,338,302

CONTROL SYSTEM FOR SUB-SEA APPARATUS Filed Aug. 24, 1964 2 Sheets-Sheet2 BOP I 3 E 5 4 2 i Z 2 7 United States Patent 3,338,302 CONTROL SYSTEMFOR SUB-SEA APPARATUS Laurence M. Hubby, Bellaire, Tex., assignor toTexaco Inc., New York, N.Y., a corporation of Delaware Filed Aug. 24,1964, Ser. No. 391,541 3 Claims. (Cl. 166-.5)

ABSTRACT OF THE DISCLOSURE Apparatus for operating blow-out preventersand such underwater wherein operating fluid is supplied from anunderwater storage vessel in response to activation from the surface andfluid in the underwater storage vessel is automatically replenished fromanother fluid storage vessel located at the surface.

This invention relates to a control system and, more particularly, to aremotely operated control system which provides fluid under highpressure for operating apparatus located in deep water.

It is necessary in connection with deep water well drilling or producingoperations to provide safety apparatus to shut off the well which ispositive in action, fast acting and which is operable from a surfacelocation. The necessity of such equipment can be appreciated not onlybecause of the extreme pressures which may be suddenly released duringdrilling of the well but also in connection with the necessity ofshutting off the well because of surface conditions such as violentstorms. This is especially important in connection with floatingdrilling rigs which must shut down the well when it is necessary totemporarily abandon the position. In such an event, all the surfaceequipment is disconnected from the sub-sea elements and the onlyremaining portions are the sub-sea well head which has mounted thereonthe blowout preventers. This equipment being located at the bottom ofthe body of water is, as can be readily realized, safe from damage bythe storm and does not present a hazard to navigation.

The usual arrangement for providing control or shut-off of the well isby means of blowout preventers which are operated by fluid pressureprovided thru control lines descending from the floating rig. Thedisadvantage of this arrangement is that the control lines mustnecessarily be of a small diameter to withstand the high pressures whichare required to operate the blowout preventers. The blowout preventersthemselves require a large volume of fluid for operation and thereforecause a large pressure dro across the control line. In order to overcomethis large pressure drop because of the large amount of fluid required,additional control lines have been added in parallel in the past.

It has been known to utilize the sea water itself as the pressureconveying fluid to operate the blowout preventers in what is commonlyreferred to as an open pressure system. However, such a system producescorrosion and sticking of the blowout preventers so that it isunreliable in operation.

Accordingly, it is the main object of the present invention to provide ahydraulic control system for operating well shut-off apparatus on asub-sea well positively and quickly without encountering theabove-mentioned disadvantages.

It is another object of the present invention to provide a well shut-offapparatus control system in which all electrical equipment is providedabove the water level for safety and accessibility.

It is a further object of the invention to provide a control system foroperating well shut-off apparatus quickly and positively which utilizesfluid in a closed system.

It is another object of the invention to provide a control system foroperating well shut-off apparatus wherein the working parts areprotected from corrosion and sticking.

Briefly stated, applicants invention comprises a control system foroperating Well shut-ofl. apparatus located under water at the Well headwhich consists of a pressurized sub-sea fluid storage vessel locatedadjacent the well shutoff apparatus for providing fluid under pressurefor operation thereof. Valves, which are controlled from remote pointsabove the water surface, are provided in the piping between thesub-surface storage vessel and the well shutoff apparatus. A fluid sumpis also provided adjacent the well head and connected to the wellshut-off apparatus to receive the fluid displaced therefrom uponoperation. A surface-located recharging means is provided for rechargingthe pressurized sub-surface storage vessel after operation of the wellshut-off apparatus. A recycling means is also provided for transferringthe fluid accumulated in the sub-sea sump as a result of an operation ofthe well shut-off apparatus to a surface located sump means which isjoined to said recharging means thereby conditioning the system for afurther operation of the blowout preventers.

The foregoing and other features and benefits of this invention aredescribed below in greater detail and are illustrated in the drawings,in which:

FIG. 1 is a schematic flow diagram of the control system showing thenecessary control tubing and piping between the control systemcomponents.

FIG. 2 is a schematic vertical section of a two-position four waycontrol valve.

FIG. 3 is a schematic vertical view showing the locations of the sub-seacomponents of the control system with respect to the sub-sea well head.

FIG. 4 is a plan view of the sub-sea components of the control systemshown in FIG. 3.

The fluid used in the control system described herein is hydraulic fluidsuch as oil which not only conveys the pressures applied thereto butalso serves as a preservative and a lubricant to minimize sticking andthereby increase the reliability of operation. It will be appreciatedthat other fluids may be used such as certain gases and still fallwithin the scope of the instant invention.

12 and 13. A further blowout preventer 14 is shown schematically indotted line form to indicate that further blowout preventers can beincluded in addition to the other blowout preventers and can beadequately controlled by adding the necessary valves in the controlsystem to take care of each additional blowout preventer. Blowoutpreventers are well known in the oil Well drilling industry and areusually connected at the well head to the top of the deepest string ofpipe which has been set and cemented in the well. The preventers areequipped with rams or equivalent elements which can be operated to sealthe annular space between the drill pipe and the string of casing towhich the blowout preventer is attached.

The underwater storage vessel 21 is located at the bottom of the body ofwater adjacent the well head and is connected to the blowout preventers12 and 13 by means of piping 22. This underwater storage vessel containsa gas such as nitrogen trapped therein which is pressurized by the fluidin the system. The nitrogen is maintained under a pressure ofapproximately 2500 p.s.i. which is considered an adequate pressure tooperate the blowout preventers. Inserted in the piping 22 are valves 23and 24 for providing control of the operation of the blowout preventers12 and 13, respectively. These valves are twoposition four-way pilotcontrolled valves. As can be seen more clearly from FIG. 2, these valveshave, in each of two positions, two distinct paths therethrough in whichthe fluid may be forced in either direction. The valves are shownoperated by pistons which are, in turn, controlled by manually operatedvalves 27 and 28 at the surface. Surface valves 27 and 28 are also ofthe twoposition four-way type, a cross-section of which would look likeFIG. 2. A variety of four-Way valves exist in the art, any one of whichcould be adapted for use in the present control system. Accordingly, adetailed explanation of the valves is not believed to be warranted. Thesurface valves 27 and 28 are shown connected to the underwater controlvalves 23 and 24 by flexible tubing 31, 32 and 33, 34, respectively. Thesurface valves 27 and 28 are connected via conduit 37 to a pressurizedsurge chamber 41. The surge chamber is pressurized only to 150 p.s.i.since the fluid pressure is only required to operate the valves. Thus,the tubing 31, 32 and 33, 34 running from the surface to the sub-surfaceequipment is not subjected to high pressures. The valves are alsoconnected to surface sump tank 51 via common conduit 35. The commonconduit 35 carries the fluid displaced by any operation of the pistonsof valves 23 and 24 to the sump tank 51.

The blowout preventers when operated displace considerable fluid whichis fed to an underwater sump tank 42 via piping 43. The sump tank 42 isoriginally vented by means of tubing 46 which extends to a two-positionvalve 94 at the surface equipment which leads in one position thereof tothe atmosphere. The sub-sea sump tank 42 is connected to the surfacesump tank via conduit 52. The surface sump tank contains a floatoperated pneumatic valve 93 which operates the two-position diaphragmcontrolled valve 94 to change from the previously mentioned ventposition to a position connecting the air compressor 95 to the sub-seasump tank 42 via conduit 46. The two-position valve 94 is returned toits vent position when the fioat 92 of float operated switching means 93reaches a predetermined height in said surface sump tank causing thepressure applied to valve 94 by valve 93 to be relieved.

The sump tank 51 is connected via conduit 53 to a pump 54 which in turnis connected to storage chamber 62 via conduit 63. A 2500 p.s.i.pressure is maintained in storage chamber 62 by pump 54 which iscontrolled by pump control switch 64 which turns on pump motor 65thereby causing pump 54 to pump the fluid from sump tank 51 to thestorage chamber until the pressure is of a sufiicient value to shut offthe pump control switch 64.

The storage chamber 62 is connected to the sub-sea storage vessel 21 viaconduit 72, valve 73 and a check valve 74. The normal flow of fluid isfrom line 72 to vessel 21 through the check valve 74. The check valvehas a needle valve 75 in parallel therewith. In the event that line 72should break, the check valve would prevent rapid lo s of pressure fromstorage vessel 21, thereby roviding time in which the blowout preventerscan be operated before the pressure is lost through needle valve 75. Theneedle valve 75 is provided so that the pressure of pressure storagevessel 21 can be read by gauge 96 at the surface. The opening of theneedle valve 75 can be very small since there is essentially no flow offluid during normal operation of the gauge. It can be seen that thisarrangement matintains the sub-sea storage vessel 21 at the required2500 p.s.i. pressure needed to provide operation of the blowoutpreventers. The transferral of the fluid from surface storage chamber 62to the sub-sea storage vessel 21 is initiated by positioning valve 73 tothe recharge position. When the pressure gauge 96 indictates the desiredpressure has been attained in the subsea storage vessel, the rechargevalve 73 can be returned to its operate position. A second output of thestorage chamber 62 is shown connected to surge chamber 41 via conduit77. A pressure reducing valve 78 is provided in the conduit 77 betweenthe storage chamber 62 and the surge chamber 41 to maintain a constantpressure in the surge chamber.

As previously mentioned, FIG. 2 shows a cross-section of a two-positionfour-way control valve such as might be used for any of the valves 23,24, 27 and 28. As can be seen, the control valve has two separate paths8'1 and 82 therethrough which are capable of passing fluid in eitherdirection. It can be seen that a rotation of the valve spool will makethe connections shown in dotted line form, thereby providing completelydiflferent paths 83 and 84 for the fluid flow. For example, consideringvalve 23, the fluid under pressure from storage vessel 21 will flowthrough the valve as shown so as to close the blowout preventer 12whereas the return fluid from the blowout preventer passes through thevalve and through piping 43 to sump tank 42. A 90 change of the valvespool will connect the fluid from pipe 22 to the open conduit going tothe blowout preventer thus opening blowout preventer 12 whereas thedisplaced fluid will pass through the conduit 25 marked close, throughthe valve 23 to the sump tank 42 via piping 43. It will be appreciatedthat other control valve arrangements could be used to perform the samefunction. For example, a single pilot two-position valve with springreturn would require only one control line per valve wherein thepressure in the control line would position the valve to hold theblowout preventer open and loss of pressure would allow the valve toclose thus providing a fail-safe control in the event that the controltubing should break.

Referring to FIG. 3 there is shown schematically the position of thesub-surface storage vessel 21 and the sump tank 42 with respect to theblowout preventers 12 and 13. The well head, designated generally as 86,is shown seated on the water bottom 87. Sub-surface storage vessel 21and sump tank 42 are shown mounted directly on the well head base 91. Itwill be appreciated that short lengths of piping such as piping 22 and43 connect the storage vessel 21 and the sump tank 42 to the controlvalve respectively. It will be appreciated that there is no limitationon the diameter of the pipe 22 and 43 because of the high operatingpressures used since they do not have to be flexible and can, therefore,be made of suitable strong metal. The relatively large diameter of thepipes and their short lengths will allow an extremely fast response ofthe blowout preventers when the control valves 23 and 24 are set fOroperation thereof since high pressures and large volume of flow can beobtained.

FIG. 4 shows a plan view of the apparatus of FIG. 3

and more particularly, shows the relationship of the control valves 23and 24 to the blowout preventers 12 and 13. The corresponding parts inFIG. 3 and FIG. 4 are designated by similar reference numerals.

The detailed operation of the blowout preventer control system startingwith the blowout preventers in the openposition will now be described.To close the blowout preventers, the operator at the remote surfacelocation would set the valves 27 and 28 into the position shownschematically in FIG. 1. This would allow the fluid from surge chamber41, which is under 150 p.s.i. pressure, to flow through both valves 27and 28, through control tubing 32 and 34, to valves 23 and 24,respectively. The fluid under pressure in control tubing 32 and 34 wouldcause the hydraulic pistons of valves 23 and 24 to position the valvesas shown in FIG. 1. Accordingly, the pressure from storage vessel 21which is under 2500 p.s.i. pressure passes through the control valves 23and 24 from piping 22 to the blowout preventers via pipes 25 and 26,each of which is marked close. The blowout preventers will, accordingly,close and the fluid displaced by the closing thereof will flow throughpipes 19 and 20, the valves 23 and 24 as shown in FIG. 1, and thrupiping 43 to sump tank 42. It will be appreciated that the blowoutpreventers can be operated simultaneously by one surface control switchor individually as shown in FIG. 1. The control system should now bereset for any further operation of the blowout preventers. This isaccomplished by operating recharge valve 73 so as to connect the surfacestorage chamber 62 which is maintained at 2.500 p.s.i. pressure to thesub-surface storage vessel 21. This will cause the pressure in storagevessel 21 to again build up to the 2500 p.s.i. pressure which is in thearea necessary for operation of the blowout preventers. As the pressurein surface storage chamber 62 drops below the 2500 p.s.i. pressure, thepump control switch automatically engages and starts the motor 65 ofpump 54 which pumps fluid from the surface sump tank 51 via conduit 53into storage chamber 62 until the pressure is again brought up to therequired 2500 p.s.i. It can be seen that a recycling of the fluid fromthe sub-sea sump tank 42 to the surface sump tank 51 is necessary. Thisis accomplished automatically by the float controlled pneumatic valve 93in the surface sump tank 51 which in turn operates two-position valve 94to disconnect the sub-sea sump tank from vent and connect it to the aircompressor 95. The air from the compressor 95 increases the pressure inthe sump tank 42 thereby causing the excess fluid accumulated therein asa result of the operation of the blowout preventer to flow to thesurface sump tank via conduit 52. As the fluid fills the surface sumptank 51, the float 92 will reach a position at which the floatcontrolled valve 93 will shut-off and, accordingly, two-position valve94 will again be operated and the sub-surface sump tank 42 is againvented to the asmosphere. Thus, the entire system is now in its initialcondition and ready for any subsequent operation of the blowoutpreventers. At this time, the. recharge valve should be placed in theoperate position. The pressure gauge 96 as previously mentionedindicates the pressure in the sub-sea storage vessel 21.

It can be seen that all of the electrical equipment of the hydrauliccontrol system is located at the control station above the sea level andthat all the necessary operating controls are also available foroperation and servicing. It can also be seen that the particular controlsystem provides fast and positive operation of the blowout preventerssince the flow of fluid under pressure to the preventers is not limitedby long lengths of small diameter conduits. Also, the system is a closedsystem thus preventing contamination of the fluid utilized in thesystem. This is important since the system must be protected fromcorrosion and sticking to provide reliability especially since thesystem in practice is operated at infrequent intervals but with maximumimportance on positive operation when needed, that is, whenever the wellthreatens to blow out.

Obviously, many modifications and variations of the invention, asherein-before set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

I claim:

1. A control system for operating well shut-off apparatus located at asub-sea well head, comprising a pressurized sub-sea fluid storage vessellocated adjacent said subsea well head, a short length of large diameterpipe connecting said pressurized sub-sea fluid storage vessel to saidwell shut-off apparatus for passing large volumes of fluid underpressure in a short time to operate said well shutoff apparatus, asub-sea fluid sump vessel located adjacent said well head, a shortlength of large diameter pipe connecting said sub-sea fluid sump vesselto said well shut-off apparatus for passing the large volume of fluid ina short time which is displaced by an operation of said shut-ofl?apparatus, a sub-sea two position four-way valve connected to both saidpressurized sub-sea fluid storage vessel pipe for selectively applyingsaid fluid under pressure to open and close said well shut-off apparatusand to said sub-sea fluid sump vessel pipe for correspondinglyselectively applying the fluid displaced by said opening and closing ofsaid well shut-0E apparatus to said sub-sea fluid sump vessel, a surfacelocated fluid pressure source, a surface located two-way four-positionvalve for connecting said surface fluid pressure source to said sub-seatwo-postion four-way valve to provide remote control operation thereof,surface located recharging means for recharging both said pressurizedsub surface fluid storage vessel after operation of said well shut-01fapparatus and said surface fluid pressure source, a surface located sumpmeans joined to said recharging means for supplying fluid thereto, andrecycling means for transferring the fluid accumulated in said subseasump vessel as a result of an operation of said well shut-off apparatusto said surface located sump means thereby conditioning said system fora further operation of said well shut-off apparatus.

2. A control system for operating apparatus located under water,comprising fluid pressure means located under water adjacent saidapparatus and connected thereto for providing fast positive operation ofsaid apparatus, sump means connected to and located adjacent saidunderwater apparatus for accumulating the fluid displaced by operationof said underwater apparatus, underwater valve means for switching thepath of the pressurized fluid to operate said underwater apparatuseither of two ways, means for controlling said underwater valve meansfrom the surface of said water, means for recycling said fluidaccumulated in said underwater sump means and means for recharging saidunderwater pressure means after an operation thereby conditioning saidsystem for a further operation of said underwater apparatus, saidrecharging means comprising a pressurized surface located storage vesseland an automatically controlled pump to maintain said storage chamber ata predetermined pressure.

3. A control system for operating apparatus located under water,comprising fluid pressure means located under water adjacent saidapparatus and connected thereto for providing fast positive operation ofsaid apparatus, sump means connected to and located adjacent saidunderwater apparatus for accumulating the fluid displaced by operationof said underwater apparatus, underwater valve means for switching thepath of the pressurized fluid to operate said underwater apparatuseither of two ways, means for controlling said underwater valve meansfrom the surface of said water, means for recycling said fluidaccumulated in said underwater sump means and means for recharging saidunderwater pressure means after an operation thereby conditioning saidsystem for a further operation of said underwater apparatus, saidrecycling means including a surface located sump means which includes afluid level responsive valve controlled by the fluid level in saidsurface located sump means, a two-position valve operated in response tosaid fluid level responsive valve and a pneumatic pressure source, saidtwo-position valve in one position connecting said underwater fluid sumpmeans to the atmosphere and in the other position connecting thepneumatic pressure source to said underwater fluid sump means to providepressure for transferring the excess fluid in said underwater fluid sumpmeans to said surface sump means.

References Cited UNITED STATES PATENTS Kofahl 175-8 X Bauer et a1.166'-.6 Haeber et a1. 166.6 Rhodes et al 175-7 Hoch 166.6 Lewis 166.6Shatto et a1 166--.5

CHARLES E. OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner.

1. A CONTROL SYSTEM FOR OPERATING WELL SHUT-OFF APPARATUS LOCATED AT ASUB-SEA WELL HEAD, COMPRISING A PRESSURIZED SUB-SEA FLUID STORAGE VESSELLOCATED ADJACENT SAID SUBSEA WELL HEAD, A SHORT LENGTH OF LARGE DIAMETERPIPE CONNECTING SAID PRESSURIZED SUB-SEA FLUID STORAGE VESSEL TO FLUIDWELL SHUT-OFF APPARATUS FOR PASSING LARGE VOLUMES OF FLUID UNDERPRESSURE IN A SHORT TIME TO OPERATE SAID WELL SHUTOFF APPARATUS, ASUB-SEA FLUID SUMP VESSEL LOCATED ADJACENT SAID WELL HEAD, A SHORTLENGTH OF LARGE DIAMETER PIPE CONNECTING SAID SUB-SEA FLUID SUMP VESSELTO SAID WELL SHUT-OFF APPARATUS FOR PASSING THE LARGE VOLUME OF FLUID INA SHORT TIME WHICH IS DISPLACED BY AN OPERATION OF SAID SHUT-OFFAPPARATUS, A SUB-SEA TWO POSITION FOUR-WAY VALVE CONNECTED TO BOTH SAIDPRESSURIZED SUB-SEA FLUID STORAGE VESSEL PIPE FOR SELECTIVELY APPLYINGSAID FLUID UNDER PRESSURE TO OPEN AND CLOSE SAID WELL SHUT-OFF APPARATUSAND TO SAID SUB-SEA FLUID SUMP VESSEL PIPE FOR CORRESPONDINGLYSELECTIVELY APPLYING THE FLUID DISPLACED BY SAID OPENING AND CLOSING OFSAID WELL SHUT-OFF APPARATUS TO SAID SUB-SEA FLUID SUMP VESSEL, ASURFACE LOCATED FLUID PRESSURE SOURCE, A SURFACE LOCATED TWO-WAYFOUR-POSITION VALVE FOR CONNECTING SAID SURFACE FLUID PRESSURE SOURCE TOSAID SUB-SEA TWO-POSITION FOUR-WAY VALVE TO PROVIDE REMOTE CONTROLOPERATION THEREOF, SURFACE LOCATED RECHARGING MEANS FOR